Substring with reverse index

Question

How can I extract  456  from  xxx 456  where xxx is of indefinite length

User · Answer

Also you can get the result by using substring and lastIndexOf -  alert  xxx 456  substring  xxx 456  lastIndexOf      1

User · Answer

The substring method allows you to specify start and end index   var str    xxx 456   var subStr   str substring str length - 3  str length

User · Answer

Although this is an old question  to support answer by user187291  In case of fixed length of desired substring I would use substr   with negative argument for its short and readable syntax   xxx 456  substr -3    For now it is compatible with common browsers and not yet strictly deprecated

User · Answer

Simple regex for any number of digits at the end of a string    xxx 456  match   d     0     456  xxx 4567890  match   d     0     4567890   or use split pop indeed      yyy xxx 45678901   split      pop      45678901

User · Answer

A crazy regex approach   xxx 456  match         0    456

User · Answer

alert  xxxxxxxxxxx 456  substr -3     caveat  according to mdc  not IE compatible

User · Answer

here is my custom function  function reverse substring str from to     var temp       var i 0    var pos   0    var append          for i str length-1 i gt  0 i--         alert  inside loop     str i        if pos    from            append true             if pos    to            append false           break            if append            temp   str i    temp            pos          alert  bottom loop     temp      var str    bala 123   reverse substring str 0 3     This function works for reverse index

User · Answer

you can just split it up and get the last element  var string  xxx 456   var a string split       alert a 1     or a pop

User · Answer

String prototype reverse           return Array prototype slice call this             reverse              join              replace    g         using a reverse string method  var str    xxx 456  str   str reverse      654 xxx  str   str substring 0 3     654  str   str reverse     456   if your reverse method returns the string then chain the methods for a cleaner solution

User · Answer

var str    xxx 456   var str sub   str substr str lastIndexOf      1     If it is not always three digits at the end  and seperated by an underscore   If the end delimiter is not always an underscore  then you could use regex    var pat      0-9  1       var m   str match pat

User · Answer

slice works just fine in IE and other browsers  it s part of the specification and it s the most efficient method too   alert  xxx 456  slice -3      - gt  456   slice Method  String  - MSDN slice - Mozilla Developer Center

[javascript] Substring with reverse index

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